[iOS] Fixed Shell Navigating event showing same current and target values (#25749)

### Issue Detail

In the Shell Navigating event, the Current and Target locations are the
same.

### Root Cause

The route comparison logic did not properly check the navigation state,
leading to redundant route values in routeStack.

### Description of Change

Updated the route validation logic to correctly compare and update
routeStack. If the new route matches the existing one at the expected
position, redundant elements in routeStack are removed to maintain an
accurate navigation state.

### Tested the behaviour in the following platforms
 
- [x] Android
- [x] Windows
- [x] iOS
- [x] Mac

### Issues Fixed
 
Fixes #25599

### Screenshots

| Before Issue Fix | After Issue Fix |
|----------|----------|
| <video width="300" height="600"
src="https://github.com/user-attachments/assets/2706b3c6-f289-4eb7-9f4a-9475898bff87">
| <video width="300" height="600"
src="https://github.com/user-attachments/assets/86c72f4c-f6b3-4a7c-b39c-2245fa93d885">)
|

Author: Vignesh-SF3580

src/Controls/src/Core/Shell/ShellNavigationManager.cs

@@ -575,6 +575,24 @@ public static ShellNavigationState GetNavigationState(ShellItem shellItem, Shell
 				}
 			}
 
+#if IOS || MACCATALYST
+			if (Shell.Current?.CurrentState?.Location is not null)
+			{
+				var currentRoute = Shell.Current?.CurrentState?.Location?.ToString();
+				if (!string.IsNullOrEmpty(currentRoute))
+				{
+					var currentPaths = new List<string>(currentRoute.Split('/'));
+					// Indices 0 and 1 of both routeStack and currentPaths are dummy/empty values
+					// The first meaningful route segment is at index 2.
+					if (currentPaths.Count == routeStack.Count && currentPaths.Count > 3 && currentPaths[2] == routeStack[2])
+					{
+						// Current route is same as the new route, so remove the last elements of the routeStack
+						routeStack.RemoveRange(3, routeStack.Count - 3);
+					}
+				}
+			}
+#endif
+
 			if (routeStack.Count > 0)
 				routeStack.Insert(0, "/");
 

src/Controls/tests/TestCases.HostApp/Issues/Issue25599_1.cs

@@ -0,0 +1,134 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 25599_1, "Shell Navigating event shows identical Current and Target on tab click", PlatformAffected.iOS | PlatformAffected.macOS)]
+public class Issue25599_1 : Shell
+{
+	public Issue25599_1()
+	{
+		var tabBar = new TabBar();
+
+		var homeTab = new Tab
+		{
+			Title = "Home"
+		};
+		var homeShellContent = new ShellContent
+		{
+			ContentTemplate = new DataTemplate(() => new Issue25599_1MainPage()),
+			Route = "MainPage"
+		};
+		homeTab.Items.Add(homeShellContent);
+		tabBar.Items.Add(homeTab);
+
+		var settingsTab = new Tab
+		{
+			Title = "Settings"
+		};
+		var settingsShellContent = new ShellContent
+		{
+			ContentTemplate = new DataTemplate(() => new Issue25599_1DetailPage()),
+			Route = "DetailPage"
+		};
+		settingsTab.Items.Add(settingsShellContent);
+		tabBar.Items.Add(settingsTab);
+		Items.Add(tabBar);
+	}
+}
+
+public class Issue25599_1MainPage : ContentPage
+{
+	Label navigatedLabel;
+	Label navigatingCurrentLabel;
+	Label navigatingTargetLabel;
+
+	public Issue25599_1MainPage()
+	{
+		var layout = new StackLayout
+		{
+			Padding = 20,
+			Spacing = 10
+		};
+
+		var button = new Button
+		{
+			Text = "Push Detail Page",
+			AutomationId = "PushButton"
+		};
+		button.Clicked += async (s, e) =>
+		{
+			await Navigation.PushAsync(new Issue25599_1DetailPage());
+		};
+
+		navigatingCurrentLabel = new Label
+		{
+			Text = "Navigating Current: Not triggered",
+			AutomationId = "MainPageNavigatingCurrentLabel",
+			FontSize = 12,
+			LineBreakMode = LineBreakMode.WordWrap
+		};
+
+		navigatingTargetLabel = new Label
+		{
+			Text = "Navigating Target: Not triggered",
+			AutomationId = "MainPageNavigatingTargetLabel",
+			FontSize = 12,
+			LineBreakMode = LineBreakMode.WordWrap
+		};
+
+		navigatedLabel = new Label
+		{
+			Text = "Navigated: Not triggered",
+			AutomationId = "MainPageNavigatedLabel",
+			FontSize = 12,
+			LineBreakMode = LineBreakMode.WordWrap
+		};
+
+		layout.Add(button);
+		layout.Add(navigatingCurrentLabel);
+		layout.Add(navigatingTargetLabel);
+		layout.Add(navigatedLabel);
+
+		Content = layout;
+		Title = "MainPage";
+
+		if (Application.Current?.MainPage is Issue25599_1 shell)
+		{
+			shell.Navigating += OnNavigating;
+			shell.Navigated += OnNavigated;
+		}
+	}
+
+	void OnNavigating(object sender, ShellNavigatingEventArgs e)
+	{
+		navigatingCurrentLabel.Text = $"{e.Current?.Location}";
+		navigatingTargetLabel.Text = $"{e.Target?.Location}";
+	}
+
+	void OnNavigated(object sender, ShellNavigatedEventArgs e)
+	{
+		navigatedLabel.Text = $"Navigated:\nPrevious: {e.Previous?.Location}\nCurrent: {e.Current?.Location}";
+	}
+}
+
+public class Issue25599_1DetailPage : ContentPage
+{
+	public Issue25599_1DetailPage()
+	{
+		var layout = new StackLayout
+		{
+			Padding = 20,
+			Spacing = 10,
+			HeightRequest = 100
+		};
+
+		var popButton = new Button
+		{
+			Text = "Pop",
+			AutomationId = "PopButton"
+		};
+
+		layout.Add(popButton);
+		Content = layout;
+		Title = "DetailPage";
+
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25599_1.cs

@@ -0,0 +1,28 @@
+#if TEST_FAILS_ON_WINDOWS && TEST_FAILS_ON_ANDROID // Clicking an already selected tab does not trigger navigation events on Windows or Android
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue25599_1 : _IssuesUITest
+{
+	public Issue25599_1(TestDevice testDevice) : base(testDevice)
+	{
+	}
+	public override string Issue => "Shell Navigating event shows identical Current and Target on tab click";
+
+	[Test]
+	[Category(UITestCategories.Shell)]
+	public void VerifyNavigatingEventOnTabReselection()
+	{
+		App.WaitForElement("PushButton");
+		App.Tap("PushButton");
+		App.WaitForElement("PopButton");
+		App.TapTab("Home");
+		var currentLabel = App.WaitForElement("MainPageNavigatingCurrentLabel");
+		var targetLabel = App.WaitForElement("MainPageNavigatingTargetLabel");
+		Assert.That(currentLabel.GetText(), Is.Not.EqualTo(targetLabel.GetText()));
+	}
+}
+#endif